Alison Sweeney is no stranger to the battle of the bulge. The Days of Our Lives star revealed her weight-loss struggles in her book, All the Days of My Lives (So Far) (Kensington, 2004), and now, as host of NBC’s The Biggest Loser, she cheers on others who trying to slim down. But this season, the Hollywood soapstar plans on gaining weight, and she has no qualms about it. Read on to learn about Sweeney’s pound-packing and weight-shedding tales. Plus: Test your celebrity weight loss IQ…

As season seven of The Biggest Loser premieres tonight on NBC, Sweeney will be watching the show’s contestants shed pounds for a $250,000 prize, all while she’s growing bigger. And she couldn’t be happier. That’s because the 32-year-old is five-months pregnant with her second child.

"We found out that it's a girl, and we're really excited about that," says Sweeney, who has a 3-year-old son, Ben, with husband David Sanov.

Don’t think the pregnancy is slowing her down. Sweeney nimbly juggles her duties as a wife, mother, TV show host, and her starring role as Sami Brady on Days of Our Lives. (Note to Days fans: No decision has been made yet on whether the pregnancy will be written into the show.)

She credits her parents for teaching her the skills that make her busy life possible.

"They taught me to take it one day at a time," Sweeney says. "Don't kill yourself thinking about what happens down the road or overwhelm yourself with how much you have on your plate. Just think: What's the best choice for me to make for my son and my husband? It's a juggling act, but it's more just finding the balance."

Fortunately, Sweeney is able to bring her son Ben to work on occasion, but when they’re not on set, the working mom prefers to be outdoors, not in front of the TV.

"You can do stuff together that's fun and energetic," she points out. "We take our son out and fly kites and go to the park. It's little stuff … that seems basic, but at the same time, it's part of a healthy dynamic.”

This season of The Biggest Loser will feature eight family teams: Four husband-and-wife couples will face off against four parent-and-child teams. Besides teaching contestants about proper diet and exercise, the show tries to help them figure out the issues that contributed to their obesity, and gives them the skills to make a permanent change. The show, which is now seen in more than 90 countries, aims to provide participants with the tools needed to maintain a new healthy lifestyle – so the weight doesn’t return.

To promote healthful eating, the show’s producers tapped New York City chef and restaurant owner Rocco DiSpirito, who gives valuable nutrition information to contestants and viewers. This season, DiSpirito plans to take the contestants food shopping, using the average American budget, to prove that anyone can eat healthy without breaking the bank.

The Biggest Loser also features expert trainers Bob Harper and Jillian Michaels, who will work with the teams at the gym and on the track. But many of the sweat-spilling workouts the contestants endure are left on the cutting-room floor.

"For me, the part that is almost heartbreaking is [that TV viewers] don't see them working out in the gym literally six to eight hours a day," Sweeney says. "They stay late. Jillian and Bob … stay until 1 a.m. with the contestants and help them early the next morning. [Viewers] don't see how comprehensive and how intense it is."

Harper and Michaels have advised Sweeney about her own workouts since she joined the series in early 2007. So it’s no surprise that she turned to them for fitness advice during her pregnancy.

"They are so careful and so concerned about me," she says. "I take Bob's spin class every week, and the last time I was there, Jillian was working out next to me to make sure that I was very careful about my heart rate. She also didn't want me to get too hot. Because they know so much about all forms of weight loss, obviously, they know what the rules are when you're pregnant."

Sweeney dismisses the myth that an expectant mother should just take it easy. Although it may seem counterintuitive, working out is a key part of a healthy pregnancy, Sweeney says. “Get out there. Go for a walk. Get some exercise that will boost your energy, give you those healthy endorphins and get the blood flowing," she says.

"You have got to stay fit," she says. "It's really healthy for the baby [for you] to stay active. You can continue to work out through your whole pregnancy, so that's my plan."

Sweeney's second pregnancy has been more difficult than her last one, she says. This time, she’s had moments of extreme morning sickness. "The first three-and-a-half months all I wanted was a bowl of cereal!" she says.

Although pregnancy is the one time a woman can eat in excess, the Emmy-winning actress says that whenever she tried to eat some of her favorite foods, such as grilled chicken or tomatoes, she would end up pushing it away because she was repelled by the smell.

Now that her morning sickness is a thing of the past, the star is craving sweets but does her best to satisfy herself with fruit instead of cake, candy or cookies.

That’s just one way Sweeney practices what her reality show preaches. At home, she cooks healthy meals for her family, sometimes using The Biggest Loser Cookbook (Rodale, 2006) for inspiration. And she makes sure Ben eats his vegetables.

"I love making dinner for my family," she says. "There is something so fulfilling about going to the farmer's market, picking out fresh ingredients and making a Sunday dinner. That is something that I feel is so important to the heart of the family and something that has been lost in recent years."

With her January due date, Sweeney knows she may miss the end of the show’s seventh season, which hasn't starting filming yet.

"I'm definitely planning on working as much as I can until the last minute … because I'm such a fan," she says. "I love being there with [the contestants]. I love seeing their progress. I don't want to have to call and ask, 'How did they do this week?' I want to be there."

What's Your Celebrity Weight Loss IQ?You can never be too rich or too thin. Or can you? Even Hollywood's hottest stars battle the bulge. Are you keeping tabs on who's losing what and how they're doing it? Put your celebrity weight loss IQ to the test.

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